Curable resin compositions containing silicone resins have been known conventionally and are used, for example, as compositions for sealing optical semiconductors.
For example, Japanese Unexamined Patent Application Publication No. 2010-001336A describes “a curable organopolysiloxane composition comprising at least: (A) a branched-chain organopolysiloxane which contains in one molecule at least three alkenyl groups and in which at least 30 mol % of all silicon-bonded organic groups is aryl groups; (B) a straight-chain organopolysiloxane that contains an aryl group and that has both molecular terminals capped with diorganohydrogensiloxy groups (in an amount so that the amount of the silicon-bonded hydrogen atoms contained in the component (B) per 1 mol of the alkenyl groups contained in the component (A) is from 0.5 to 2 mol); (C) a branched-chain organopolysiloxane that contains in one molecule at least three diorganohydrogensiloxy groups and at least 15 mol % of all silicon-bonded organic groups is aryl groups (in an amount so that the amount of the diorganohydrogensiloxy groups contained in the component (C) is from 1 to 20 mol % relative to the total amount of the diorganohydrogensiloxy groups contained in the component (B) and in the component (C); and (D) a hydrosilylation catalyst (in an amount that accelerates curing of the composition)” ([Claim 1]).
Furthermore, in Working Examples 1 and 3 described in the “Examples” section of Japanese Unexamined Patent Application Publication No. 2010-001336A, a substance with a degree of polymerization of 1 is used as the (B) straight-chain organopolysiloxane having an aryl group and having both molecular terminals capped with diorganohydrogensiloxy groups.
Furthermore, Japanese Unexamined Patent Application Publication (translation of PCT application) No. 2012-507582A describes “a hydrosilylation reaction-curable organopolysiloxane composition comprising: (A) a methylphenylalkenylpolysiloxane that has at least two silicon-bonded alkenyl groups in one molecule, wherein 5 mol % or less of all siloxane units is diphenylsiloxane units and at least 20 mol % of all silicon-bonded organic groups in the molecule is phenyl groups, (B) a methylphenylhydrogenpolysiloxane that has at least two silicon-bonded hydrogen atoms in one molecule, wherein 5 mol % or less of all siloxane units is diphenylsiloxane units and at least 20 mol % of all silicon-bonded organic groups in the molecule is phenyl groups, and (C) a hydrosilylation reaction catalyst; wherein an amount of the diphenylsiloxane units in this composition is 5 mol % or less of the amount of all siloxane units” ([Claim 1]).
In recent years, the performance level required for curable resin compositions containing silicone resins has increased, and there is a demand for better adhesion to adherends, in particular.
When investigating the “curable organopolysiloxane composition” disclosed in Japanese Unexamined Patent Application Publication Nos. 2010-001336A and 2012-507582A, the inventors of the present technology found that the adhesion of the cured product is insufficient depending on the type of the adherend and environment after the curing.
The present technology provides a curable resin composition having excellent adhesion to adherends.
Use of a curable resin composition containing a straight-chain organopolysiloxane having a predetermined functional group and an average degree of polymerization of greater than 10,and a branched-chain organopolysiloxane having a predetermined functional group, the curable resin composition having a proportion of diphenylsiloxane units relative to an amount of all siloxane units of 10 mol % or greater, leads to excellent adhesion to various adherends, according to the present technology.
Specifically, the present may be described by the following features.
[1] A curable resin composition comprising:
(A) a straight-chain organopolysiloxane having at least two silicon-bonded hydrogen atoms and at least one aryl group in one molecule and having an average degree of polymerization of greater than 10;
(B) a branched-chain organopolysiloxane having at least three alkenyl groups and at least one aryl group in one molecule; and
(C) a hydrosilylation reaction catalyst;
wherein a proportion of diphenylsiloxane units relative to an amount of all siloxane units is 10 mol % or greater, and the all siloxane units containing siloxane units derived from the straight-chain organopolysiloxane (A) and the branched-chain organopolysiloxane (B).
[2] The curable resin composition according to [1], where a total content of a cyclic organosiloxane having a molecular weight of 150 to 1,200 is 7.5 mass % or less.
[3] The curable resin composition according to [1] or [2], where the average degree of polymerization of the straight-chain organopolysiloxane (A) is greater than 30.
[4] The curable resin composition according to any one of [1] to [3], where the branched-chain organopolysiloxane (B) is an organopolysiloxane represented by average unit formula (4) below:(R3SiO3/2)a(R32SiO2/2)b(R33SiO1/2)c(SiO4/2)d(X1O1/2)e  (4)
In Formula (4), each R3 moiety is independently a substituted or unsubstituted monovalent hydrocarbon group; however, in one molecule, at least three of the R3 moieties are alkenyl groups, and at least one R3 moiety is an aryl group.
In Formula (4), X1 is a hydrogen atom or alkyl group. In Formula (4), a is a positive number; b is 0 or a positive number; c is 0 or a positive number; d is 0 or a positive number; e is 0 or a positive number; b/a is a number in a range of 0 to 10; c/a is a number in a range of 0 to 0.50; d/(a+b+c+d) is a number in a range of 0 to 0.3; and e /(a+b+c+d) is a number in a range of 0 to 0.4.
[5] The curable resin composition according to any one of [1] to [4], further comprising a straight-chain organopolysiloxane (G) represented by Formula (6) below:HR22SiO(R22SiO)kSiR22H  (6)
In Formula (6), each R2 moiety is independently an alkyl group, aryl group, hydroxy group, or alkoxy group, and at least one of the R2 moieties is an aryl group.
In Formula (6), k is a positive number of 1 to 5.
The curable resin composition according to any one of [1] to [5], where the composition is a composition for sealing an optical semiconductor element.
With the present technology, a curable resin composition having excellent adhesion to adherends can be provided.